cannot convert boost::lambda::… to long long unsigned int

Question

I have a simple program using boost 1.56 headers:

#include <boost/lambda/lambda.hpp>
#include <boost/lambda/bind.hpp>
#include <algorithm>
#include <iostream>

int main(int argc, char* args[])
{
  size_t a[] = { 1, 2, 3, 4 };
  size_t b[] = { 5, 6, 7, 8 };
  std::transform(a, a+4, b, a, (boost::lambda::_1 + boost::lambda::_2));
  for (int i=0; i<4; ++i)
    std::cout << a[i] << ", ";
  std::cout << std::endl;

  return 0;
}

which is compiled by g++-4.9.1 on Debian Linux and runs fine, both for 32bit and 64bit architectures.

also i686-w64-mingw32-g++ (4.9.1) cross-compiles and runs fine.

however x86_64-w64-mingw32-g++ (4.9.1) fails to cross-compile for 64bit architecture like this:

$ x86_64-w64-mingw32-g++ -I/opt/win64/include transform.cpp -static
In file included from /usr/lib/gcc/x86_64-w64-mingw32/4.9-win32/include/c++/algorithm:62:0,
             from /opt/win64/include/boost/core/swap.hpp:25,
             from /opt/win64/include/boost/utility/swap.hpp:15,
             from /opt/win64/include/boost/tuple/detail/tuple_basic.hpp:40,
             from /opt/win64/include/boost/tuple/tuple.hpp:28,
             from /opt/win64/include/boost/lambda/core.hpp:28,
             from /opt/win64/include/boost/lambda/lambda.hpp:14,
             from transform.cpp:1:
/usr/lib/gcc/x86_64-w64-mingw32/4.9-win32/include/c++/bits/stl_algo.h: In instantiation of ‘_OIter std::transform(_IIter1, _IIter1, _IIter2, _OIter, _BinaryOperation) [with _IIter1 = long long unsigned int*; _IIter2 = long long unsigned int*; _OIter = long long unsigned int*; _BinaryOperation =    boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >]’:
transform.cpp:11:92:   required from here
/usr/lib/gcc/x86_64-w64-mingw32/4.9-win32/include/c++/bits/stl_algo.h:4202:12: error: cannot convert ‘boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >::sig<boost::tuples::tuple<long long unsigned int&, long long unsigned int&, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >::type {aka boost::lambda::detail::return_type_deduction_failure<boost::lambda::detail::return_type_2_arithmetic_phase_3<long long unsigned int, long long unsigned int> >}’ to ‘long long unsigned int’ in assignment
  *__result = __binary_op(*__first1, *__first2);
            ^
In file included from /opt/win64/include/boost/lambda/lambda.hpp:22:0,
                 from transform.cpp:1:
/opt/win64/include/boost/lambda/detail/operator_lambda_func_base.hpp: In instantiation of ‘RET boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, Args>::call(A&, B&, C&, Env&) const [with RET = boost::lambda::detail::return_type_deduction_failure<boost::lambda::detail::return_type_2_arithmetic_phase_3<long long unsigned int, long long unsigned int> >; A = long long unsigned int; B = long long unsigned int; C = const boost::tuples::null_type; Env = const boost::tuples::null_type; Args = boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>]’:
/opt/win64/include/boost/lambda/detail/lambda_functors.hpp:211:39:   required from ‘typename boost::lambda::lambda_functor<Base>::inherited::sig<boost::tuples::tuple<A&, B&> >::type boost::lambda::lambda_functor<Base>::operator()(A&, B&) const [with A = long long unsigned int; B = long long unsigned int; T = boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >; typename boost::lambda::lambda_functor<Base>::inherited::sig<boost::tuples::tuple<A&, B&> >::type = boost::lambda::detail::return_type_deduction_failure<boost::lambda::detail::return_type_2_arithmetic_phase_3<long long unsigned int, long long unsigned int> >]’
/usr/lib/gcc/x86_64-w64-mingw32/4.9-win32/include/c++/bits/stl_algo.h:4202:46:   required from ‘_OIter std::transform(_IIter1, _IIter1, _IIter2, _OIter, _BinaryOperation) [with _IIter1 = long long unsigned int*; _IIter2 = long long unsigned int*; _OIter = long long unsigned int*; _BinaryOperation = boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >]’
transform.cpp:11:92:   required from here
/opt/win64/include/boost/lambda/detail/operator_lambda_func_base.hpp:160:72: error: could not convert ‘(boost::lambda::detail::select<boost::lambda::placeholder<1>, long long unsigned int, long long unsigned int, const boost::tuples::null_type, const boost::tuples::null_type>((* & boost::tuples::get<0, boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::cons<boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type> >((* &((const boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >*)this)->boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >::args.boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>::<anonymous>))), (* & a), (* & b), (* & c), (* & env)) + boost::lambda::detail::select<boost::lambda::placeholder<2>, long long unsigned int, long long unsigned int, const boost::tuples::null_type, const boost::tuples::null_type>((* & boost::tuples::get<1, boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::cons<boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type> >((* &((const boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >*)this)->boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> >::args.boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>::<anonymous>))), (* & a), (* & b), (* & c), (* & env)))’ from ‘long long unsigned int’ to ‘boost::lambda::detail::return_type_deduction_failure<boost::lambda::detail::return_type_2_arithmetic_phase_3<long long unsigned int, long long unsigned int> >’
        detail::select(boost::tuples::get<1>(args), CALL_ACTUAL_ARGS); \
                                                                    ^
/opt/win64/include/boost/lambda/detail/operator_lambda_func_base.hpp:206:1: note: in expansion of macro ‘BOOST_LAMBDA_BINARY_ACTION’
 BOOST_LAMBDA_BINARY_ACTION(+,arithmetic_action<plus_action>)
 ^

Yeah, TL;DR

basically something went wrong with boost::lambda::_1 + boost::lambda::_2 in combination with size_t (other types like int seem to be OK).

Why is there a problem? is that a bug in boost?

Answer 1

This is reproducible on Coliru if the types are declared unsigned long long instead of size_t . long long also fails.

This looks like a bug in boost. Their massively complicated template machinery for operator return type deduction (in all likelihood mostly if not entirely obsoleted by decltype in C++11) doesn't support long long or unsigned long long (it was written well before either was added to the C++ standard). The problem only manifested with size_t in 64-bit MinGW because that's the only platform on which long is 32 bit but size_t needs to be 64 bit, necessitating the use of long long .